Heavy oil-solid composition and method for preparing the same

ABSTRACT

The invention includes a compositon of matter comprising a heavy oil having dispersed therein surface modified solid wherein said surface modified solids comprise solids having adsorbed thereon air oxidized polar hydrocarbons from said heavy oil and wherein said surface modified solids have a diameter of about 10 microns or less and a method for preparing the same.

This application is a Divisional of U.S. Ser. No. 09/819,361 filed Mar.28, 2001, now U.S. Pat. No. 6,524,468 based on Provisional U.S. SerialNo. 60/199,571 filed Apr. 25, 2000.

FIELD OF THE INVENTION

The invention is directed to a composition of matter having improvedviscoelastic properties and a method for preparing the same.

BACKGROUND OF THE INVENTION

Refineries are faced with the task of upgrading heavy oils such as residor bitumen which is an expensive undertaking, or finding a use for it.One use for the heavy oil is in the preparation of asphalts and roofingtiles. Currently, methods for improving the properties of heavy oilsutilized for asphalts and roofing tiles include air blowing and polymermodification. What is needed in the art are ways of economicallyutilizing heavy oils and for affording materials with improvedproperties for use in items which typically employ heavy oils, such asasphalts and roofing tiles.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts Viscosity in poise (Y-axis) VERSUS 1000/temperature (K)for Arab Heavy Vacuum Resid, air oxidized Arab Heavy Vacuum Resid andair oxidized Arab Heavy Vacuum Resid with bentonite solids.

FIG. 2 depicts the elastic modulus (Y-axis) in dyne/cm², versusfrequency (X-axis) for Arab Heavy Vacuum Resid, air oxidized Arab HeavyVacuum Resid and air oxidized Arab Heavy Vacuum Resid with bentonitesolids.

FIG. 3 depicts viscous modulus (dyne/cm²) Y-axis, versus Frequency(X-axis) for Arab Heavy Vacuum Resid, air oxidized Arab Heavy VacuumResid and air oxidized Arab Heavy Vacuum Resid with bentonite solids.

SUMMARY OF THE INVENTION

The invention includes a composition of matter comprising a heavy oilhaving dispersed therein surface modified solids wherein said surfacemodified solids comprise solids having adsorbed thereon air oxidizedpolar hydrocarbons from said heavy oil.

The invention also includes a method of producing a composition ofmatter said method comprising thermally treating a mixture of heavy oiland solids having wherein said solids have a total surface area of about1500 square microns or less in the presence of oxygen for a time and ata temperature sufficient to produce oxidized polars from said heavy oiland to allow said oxidized polars to adsorb onto the surface of saidsolids wherein said adsorption achieves at least 50% coverage.

The invention also includes a product prepared by the process describedabove.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides for a composition of matter comprising a heavyoil and solid and a method for preparing the same. As used herein, aheavy oil is an oil having an API gravity of less than or equal to 20.

The method includes the step of thermally treating a mixture of heavyoil and solids for a time and at a temperature sufficient to produceoxidized polars from said heavy oil and to allow said oxidized polars toadsorb to the surface of said solids. Preferably, the solids and heavyoil will be mixed prior to and during the thermal treatment. Typically,the temperature will range from about 120 to about 220° C., preferablyabout 130 to about 180° C. The time may range from about 15 minutes toabout 6 hours, preferably from about 3 to about 5 hours. During thethermal treatment, the mixture is purged with an oxygen source which maybe oxygen, air or any other oxygen-containing source. Typically, the airor oxygen purged will be conducted at a rate of about 20 to about 150scfs/barrel, preferably about 60 to 100 scfs/barrel of heavy oil.

The solids may be selected from a variety of materials includinginorganic and organic solids. For example, inorganic solids may includefumed silica, sold under the trade name of Aerosil 130, bentonite clays,divided or delaminated bentonite clay gel, kaolinite clays, and mixturesthereof. The organic solids may include, for example carbanaceous solidssuch as soot and coke fines, or mixtures thereof. The solids, ifspherical are preferably in the size range of about 20 microns or lessin diameter, more preferably less than 10 micron, even more preferablyless than 5 microns, and most preferably about 2 micron or less, morespecifically 100 nanometers or less. The solids, if non-spherical orspherical, preferably have a total surface area of about 1500 squaremicrons or less. The preferred treat rate for the solids is 0.05 to 20.0wt %, based on the weight of the oil, more preferably, 0.1 to 2.0 wt %.The preferred materials are clays, specifically montmorillonite clayssuch as bentonite. Preferably, the clays will be a gel comprisingdelaminated or divided sheets of clay. The solid particles must alsoremain dispersed or undissolved in the oil. It is preferred that thesolid particles are hydrophilic solids. The hydrophilicity of the solidscan be determined by water wettability methods known in the art.

The solids utilized herein may exhibit a tendency to clump or aggregateprior to thermal treatment. The phenomena of aggregation is known in theart and its origin is attributed to primarily weak physical attractionforces. The size of the solids herein is the size of the individualisolated solid particle and not that of the aggregate. During thethermal treatment, the mixture of solids and heavy oil is mixed atelevated temperatures. The shearing forces accompanying the mixing atelevated temperatures are sufficient to de-aggregate the solids. If thesolids are added post thermal treatment the mixture is subjected to highshear mixing preferably in the range of 7000 to 12000 rpm of the mixingpaddle. It is preferred to add the solids prior to thermal treatment.Regardless of whether or not the solids utilized herein aggregate, thecomposition produced will exhibit improved viscoelastic properties.

The compositions of the current invention exhibit unique rheologicalproperties. The viscosity of the compositions are higher than either theheavy oil itself or thermally air oxidized heavy oil having no solidsadded thereto. They exhibit shear thinning (non-Newtonian) behavior atlow temperatures and the transition from non-Newtonian to Newtonianbehavior occurs at about 80 to 100° C. Further, these compositions arestrongly viscoelastic in the temperature range of 40° C. to 150° C. asrevealed by the experimentally determined viscous and elastic modulusprofiles. Increased enthalpy of melting observed for the compositioncompared to the untreated heavy oil or air oxidized heavy oil indicatesan improved thermoplastic property. The compositions of this inventionhave potential uses in applications where thermoplasticity andviscoelasticity of the heavy oil is a key property influencingperformance eg., asphalt for roads and roofing tiles. The extent ofimprovement for the compositions will depend on the heavy oil and solidmixture utilized.

The heavy oil used to prepare the composition of the current inventioncan be oil of any type or composition, including but not limited tocrude oil, refined oil, oil blends, chemically treated oils, resids,thermally treated oils, bitumen and mixtures thereof. Preferably, theoil should contain a sufficient amount (at least about 0.5 wt % to about40 wt %, preferably at least about 0.5 to about 13 wt %) of asphaltenes,polar hydrocarbons, or polar resins to enhance the solid-particle-oilinteraction. Crude oil residuum that is obtained from the atmosphericpipestill or vacuum pipestill of a petroleum refinery is best suited forthe invention. Heavy hydrocarbons like bitumen are also useful inpreparing the compositions herein described.

Treating the mixture of oil and solid particles in the presence of asource of oxygen causes various reactions to occur in the oil and on thesurface of the solid particles. The aromatic components of the oil thathave benzyllic carbons and those that have fused rings that areoxidizable including, but not limited to naphthalene and anthracene, areoxidized to the corresponding acids, ketones or quinine products. Organosulfur and nitrogen compounds present are oxidized to sulfoxides andnitrogen oxides. The oxygenated compounds are more surface-active thanthe aromatic components themselves and absorb strongly on the surface ofthe solid particles to improve the physical properties of thecomposition. If naphthenic acids are present as salts of divalentcations like calcium, air oxidation can convert these salts tonaphthenic acids and the corresponding metal oxide, for example calciumoxide. The free naphthenic acid can adsorb on the surface of the solidsand also improve the physical properties of the composition. Thermaltreatment with an oxygen source purge dehydrates the solid particles andthus modifies the solids' surface to improve its interaction with thesurface-active components of oil (preexistent in the oil or generatedfrom air oxidation). The solid particles may be added before, during orafter the thermal air oxidation step. However, it is preferred to addthe solids to the oil and then oxidize the mixture.

If bentonite is used as the solid particle, it may be used in divided ordelaminated form as a gel. When the gel is added to the oil andsubjected to the thermal treatment in the presence of an oxygen source,for example, air or oxygen, water is expelled from the reaction vesselas steam.

The thermal treatment reaction should be carried out until at least 80%of the water present in the mixture is expelled, preferably until 95% ofthe water is expelled, and even more preferably until 99% of the wateris expelled.

The amount of solid particle added to the oil can vary in the range ofabout 1% to 30% based on the weight of the oil. At the higherconcentrations, the mixture of solids and heavy oil will be a highsolids content slurry. When divided bentonite gel is used as the carrierfor the bentonite solid, the amount of gel added to the oil beforeoxidation can vary in the range of 5 to 95% of gel based on the weightof the oil. The weight of bentonite clay solids in the gel can vary from1 to 30% based on the weight of the water. Bentonite clay gel can easilybe prepared by delamination or peptization methods known in the art. AnIntroduction to Clay Colloid Chemistry by H. van Olphen second EditionJohn Wiley & Sons provides a description of peptizing and delaminationmethods practiced in the art.

Catalysts may be used to enhance the oxidation reaction. The oxidationcatalyst may be selected from catalysts containing iron, nickel,manganese, and mixtures thereof. The catalyst can be added to thethermal treatment as finely divided metal or oil soluble metal saltssuch as iron naphthenate and can be used to catalyze oxidation rates andeffect selectivity in the oxidation products. Such oxidation promotingcatalysts and the techniques of using such catalysts are well known inthe art. Oxidation can be conducted at elevated pressures of about 30 toabout 100 psi to further catalyze the reaction rate and achieve productselectivity, however, oxidation at ambient pressures is preferred.

The following examples are illustrative and are not meant to be limitingin any way.

EXAMPLE-1

In a typical experiment, 200 g of a mixture of Arab Heavy vacuum resid(AHVR) & 5 g Aerosil 130 (product of Degussa Corp) silica was placed ina Parr autoclave or three-necked glass flasks and oxidized attemperatures of 150 to 180° C. for 2 to 6 hours with a continuous purgeof air at 80 to 100 scf/bbl/hour. After completion of reaction a productcomprising the resid-silica composition is obtained.

EXAMPLE-2

Arab Heavy vacuum resid and bentonite gel is first mixed to form slurry.Air or oxygen gas is purged into the reactor at 80 to 100 scf/bbl/hourand the temperature raised to between 150° C. and 170° C. The water isexpelled as steam and can be condensed outside for recovery and reuse.The temperature is maintained between 150° C. and 170° C. for 4 to 6hours.

A mixture of 200 grams (g) Arab Heavy vacuum resid and 20 g of dividedbentonite gel (providing an oil to gel ratio of 10:1, and with abentonite solids concentration of 3.5 wt % in the gel) was heated to atemperature of 160° C. for 4 hours with an air purge of 80 scf/bbl/hour.About 19.6 g of water was expelled from the reactor. After completion ofreaction the product was tapped hot from the reactor.

EXAMPLE-3

A mixture of 100 grams (g) Arab Heavy vacuum resid and 30 g of dividedbentonite gel (providing an oil to gel ratio of 10:3, and with abentonite solids concentration of 3.5 wt % in the gel) was heated to atemperature of 160° C. for 4 hours with an air purge of 80 scf/bbl/hour.About 29 g of water was expelled from the reactor. After completion ofreaction the product was tapped hot from the reactor.

EXAMPLE-4 Comparative Example—Air Oxidized Resid without Solids

200 g of Arab Heavy vacuum resid was placed in a three-necked glassflask and heated to a temperature of 150 to 180° C. for 4 hours with acontinuous purge of air at 80 to 100 scf/bbl/hour. After completion ofreaction the product was tapped hot from the reactor.

Products from examples 1-4 and the untreated resid were subjected to thefollowing analyses:

a) Chemical analyses

ATRA scan analyses-silica micro column chromatography;

¹³ Nuclear Magnetic Resonance

ourier Transform Infrared (FTIR)

b) Viscosity as a function of shear rate

c) Viscosity as a function of temperature

d) Viscoelasticity to determine the elastic modulus and viscous modulus

Results from the IATRA scan chromatography analyses of the resid beforeand after thermal treatment confirmed that the thermal treatment processconverts about 15% of the aromatic fraction into oxidized compounds.Furthermore, 24% of the heaviest fraction of the resid (or asphaltenelike polars) is also converted to lower molecular weight oxidizedcompounds. C¹³NMR and FTIR identified the oxidized compounds as ketones,carboxylic acids, anhydrides and aldehydes.

Viscosity as a function of shear rate profiles for the untreated ArabHeavy Vacuum resid, air-oxidized resid and one possible resid-claycomposition of the invention at 0.4 wt % bentonite were determined. Theresid-clay composition exhibited a higher viscosity than the resid orair oxidized resid at any given temperature and shear rate in the 40 to140° C. temperature and 10⁻⁵ to 10² shear rate ranges. At lowertemperatures the resid-clay composition exhibited shear thinning ornon-Newtonian viscosity behavior. The temperature at which thecomposition transitions from shear thinning to shear independentviscosity is higher (80° C.) for the resid-clay composition. This resultis indicative of stronger network microstructure for the resid-claycomposition compared to the resid or air oxidized resid.

Viscosity as a function of 1/temperature plots for the resid, airoxidized resid and resid-clay composition are shown in FIG. 1.

Treating viscosity analogous to a rate process & fitting the data to theAndrade-Eyring equation (simple Arrhenius behavior) two processes arerecognized (a slow and a fast process) with different slopes or energiesof activation. For the resid-clay composition the energies of activationare higher and transition from the fast to slow process occurs at alower temperature. This observation suggests a difference in networkmicrostructure for the resid-clay composition compared to the resid orair oxidized resid.

Treating viscosity as a function of 1/temperature plots according tofree volume & glass transition theory and using theWilliams-Landel-Ferry equation one can obtain the glass transitiontemperature (T_(g)), free volume fraction at glass transition(f_(g)=V_(f)/V) and difference in coefficients of thermal expansionbelow and above the glass transition point (α). Results for the resid,air oxidized resid and resid-clay composition are given Table 1. Theresid-clay composition exhibits a lower f_(g) and lower α compared tothe resid or air oxidized resid. α⁻¹ is a measure of activation energy,smaller α for the resid-clay composition indicates larger activationenergy for the composition. These results suggest a stronger networkmicrostructure for the resid-clay composition compared to the resid orair oxidized resid.

Viscoelastic properties of compositions are expressed in terms of lossmodulus (G″) and storage modulus (G′). G″ and G′ represent the viscousand elastic components of the response of the material to an appliedstrain. A Rheometric Scientific Rheometer was used to determine G′ andG″ in the oscillatory mode. G′ and G″ as a function of frequency sweepwere determined for a fixed sinusoidal oscillation in the 40 to 140° C.temperature range. G′ and G″ at 60° C. for resid, air oxidized resid andresid-clay compositions (at 0.4 wt % bentonite) are given in FIGS. 2 and3 respectively. An increase in the elastic modulus and viscous modulusoccur due to air oxidation. Air oxidation with bentonite results in afurther increase in the elastic and viscous modulus.

TABLE 1 Air Oxidized Air Oxidized AHVR + AHVR AHVR Bentonitef_(g)(V_(f)/V) = 2.6767 × 10⁻² 2.6017 × 10⁻² 2.3867 × 10⁻² α(K⁻¹) =4.1465 × 10⁻⁴ 3.5195 × 10⁻⁴  2.524 × 10⁻⁴ T_(g)(° C.) = −3.1664 6.74135.7428 f_(g)(V_(f)/V) free volume fraction at T_(g) α(K⁻¹) diiference incoefficient of thermal expansion above and below the T_(g) T_(g)(° C.)glass transition temperature

What is claimed is:
 1. A method of producing a composition of mattersaid method comprising thermally treating a mixture of heavy oil andsolids, wherein each of said solids has a total surface area of about1500 square microns or less, in the presence of oxygen for a time and ata temperature sufficient to produce oxidized polars from said heavy oiland to allow said oxidized polars to adsorb onto the surface of saidsolids wherein said adsorption achieves at least 50% coverage.
 2. Themethod of claim 1, wherein said thermal treatment is conducted at atemperature of about 120° C. to about 220° C.
 3. The method of claim 1,wherein said thermal is conducted in the presence of an oxidationcatalyst.
 4. The method of claim 3 wherein said oxidation catalyst isselected from a catalyst containing iron, manganese, nickel or mixturesthereof.
 5. The method of claim 1, wherein said solid particles arepresent in said mixture in the range of about 0.05 to 20 wt % based onthe weight of oil.
 6. The method of claim 1 wherein about 1 to about 30wt % solids are present based on the weight of said oil.
 7. The methodof claim 1 wherein the solids are added to the oil as a gel or slurry.8. The method of claim 7 wherein said gel comprises about 1 to about 10wt % clay solids and about 90 to about 99 wt % water.
 9. The method ofclaim 7 wherein said gel is in the range of 5 to 95% of gel based on theweight of said oil.
 10. The method of claim 1 wherein said solidparticles are selected from inorganic and organic solids selected fernthe group consisting of fumed silica, bentonite clays, bentonite claygel, divided or delaminated bentonite clay gel, kaolinite clays, cokefines soot and mixtures thereof.
 11. The method of claim 1 wherein saidheavy oil is selected from the group consisting of crude oil, thermallytreated oil, chemically tested oil, crude oil residuum, bitumen, ormixtures thereof.
 12. The method of claim 1 wherein said solids arespherical or non spherical.
 13. The method of claim 11 wherein saidsolids are spherical they have an individual isolated particle diameterof about 20 microns or less.